1. Field of the Invention
This invention is in the field of thermally powered heat transfer systems, and more particularly relates to refrigeration systems which use heat to cool a structure. This invention incorporates a new general method of using heat to accomplish the cooling of a structure in that the invention actively utilizes two different heat sources having different temperatures, of which at least the lower temperature heat source is within the structure to be cooled, and in that it employs a new type of compressor capable of acting with positive compressive force in both of two possible compressive action directions. This new general method and this invention are of major significance in this era of energy shortages because they permit relatively small temperature differences to be made useful in accomplishing the cooling of structures.
2. Description of the Prior Art
Previous inventions in the field of thermally powered refrigeration systems used one of two general methods to cool a structure. One of these general methods, known as the absorption cycle, is dependent upon a refrigerant being soluble in an absorbent and upon that refrigerant being more soluble in that absorbent when pressure is increased, the increase in pressure being produced by heat from some heat source. For efficient operation absorption cycle systems require a temperature of at least 200.degree. F. The general method used in the current invention is not related to the absorption cycle.
The second general method used in the field of thermally powered refrigeration systems involves the use of a single, external heat source and various means of converting thermal energy into mechanical energy which is then transmitted by some means in a manner which drives the compressor of a traditional compressor cycle refrigeration system. For efficient operation such systems require a temperature of at least 165.degree. F. The general method used in the current invention is only superficially related to such systems in that this invention, as do existing systems, uses an external heat source to vaporize a refrigerant and uses two heat transfer units which function as evaporators and two heat transfer units which function as condensers. Also, both existing systems and the current invention employ compressors but the design and method of operation of the new type of compressor employed in the current invention differs greatly from the design and method of operation of existing compressors used in existing systems. The current invention uses two heat sources rather than one to power the compressor and the high temperature, external heat source need not have a temperature higher than 115.degree. F.